Stranger With My Face by Lois Duncan (1990, Paperback, Reissue)

I'd highly recommend this book for the young reader, however as an adult I found the book to be a good read too. Laurie experiences the feeling that someone is watching her and her friends and family accuse her of being in places where she could not be. The sensations of being watched slowly become clearer and clearer until finally the Watcher appears. But the Watcher disappears as if by magic. At first Laurie seeks out the Watcher but almost too late finds out the Watcher is not exactly the person she presents herself to be and her reasons for encouraging Laurie to seek her out are not to Laurie's benefit. Should I say if the book ends on a happy note or tell you if the Watcher succeeds in taking over Laurie's life? I think not!